An exquisitely preserved skull of a tiny-brained human ancestor has been recovered from excavations beneath the ruins of a medieval castle in the republic of Georgia. The skull is about 1.8 million years old and belongs to the first group of humans to migrate out of Africa, reports an international team of archaeologists.
The find calls into question a widely held hypothesis that the evolution of big brains propelled the exodus of early humans out of Africa.

The fossil evidence from Dmanisi now includes three skulls, several jaw fragments, and hundreds of stone tools and animal remains. All of the material has been recovered from the same layer of sediment. It is forcing scientists to come up with alternative explanations for why humans were able to leave Africa.

"Before this find, the main reason was that at least these humans had big brains," said David Lordkipanidze, a paleoanthropologist at the Georgian State Museum in Tbilisi who led the excavation team. "Now this shows that [their brains] were quite small."

The brain of the new specimen from Dmanisi is about half the size of a modern human's brain. The two skulls found in 1999 at the site are also about 1.8 million years old and had room for substantially larger brains.

Above: This Homo erectus skull was found in Dmanisi, Georgia.

Below: Abesalom Vekua (left) and David Lordkipanidze with Homo erectus fossils found in Dmanisi, Georgia.

This research was funded in part by the National Geographic Society's Committee for Research and Exploration (CRE).
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The research by Lordkipanidze and colleagues is published in the July 5 issue of the journal Science and is the subject of the cover story of the August issue of National Geographic magazine.

Treasure Trove

Dmanisi sits on a promontory formed by the confluence of two rivers between the Black Sea and the Caspian Sea about 50 miles (80 kilometers) southwest of Tbilisi. Archaeologists first began excavating the remains of a 1,000-year-old castle located on the site in 1936.

In 1983, while examining an ancient garbage pit, one of the archaeologists uncovered what Abesalom Vekua, a team member from the Georgian State Museum, identified as a tooth of a rhinoceros, an odd creature to have been wandering the Caucasus Mountains. Speculation about what lay in the sediments beneath the castle spurred further excavations.

Stone tools recovered in 1984 and the two skulls discovered in 1999 were all dated to 1.8 million years ago, making the site a rare treasure trove for scientists interested in human evolution.

"We can say this is the richest material from this time period from one site and from one strata," said Lordkipanidze. "Usually we have isolated finds. Now on one geological level you have three skulls and three mandibles. We have a chance to study isolated specimens and to study populations."

In addition, members of the excavation team have found thousands of plant impressions, carbonized plant remains, numerous animal bones, snail shells, and what appears to be plant pollen in a series of thick lake deposits just to the south of the Dmanisi site.

"This documents our ability to reconstruct an environmental history of the site before, during, and after the occupations with detail and precision that would be enviable in any archaeological setting," said Reid Ferring, an archaeologist at the University of North Texas in Denton and member of the excavation team.

"Also, the lake shore deposits provide us with a superb tool for locating other areas where those people camped or butchered animals," he added.

Wider Species Variation

Lordkipanidze and his colleagues have classified all three skulls as belonging to Homo erectus. However, they caution that the small brain and other features of the new skull suggest a close resemblance to Homo habilis, which was more apelike with a thin brow, huge canine teeth, and long, dangling arms.

The variation among the hominids recovered at Dmanisi makes it difficult to say exactly who these people were, said Lordkipanidze. He suggests that the variation may force scientists to rethink the definition of "Homo."

"The Dmanisi fossils show much more variation than we would have expected from any group of humans at that time," said Ferring. "But clearly, the notion that the African exodus had to await emergence of a tall, fast, strong, and clever species and that Homo erectus was our first ancestor to meet all those requirements was wrong."

The researchers conclude that the Dmanisi hominids are among the most primitive individuals attributed to H. erectus and that "it now seems that the first humans to disperse from the African homeland were similar in grade to H. habilis."

The range of material found at the Dmanisi site "will help us understand the evolutionary origins of these early humans, their variation, and their affiliation to other early human groups," said Chris Stringer, a paleontologist at the Natural History Museum in London, England.

Out of Africa

Prior to the discoveries at Dmanisi, scientists theorized that the first humans to migrate out of Africa had large brains and wielded advanced stone tools such as hand axes that allowed them to butcher and process meat.

The stone tools found with the hominid remains at Dmanisi, however, are simple choppers and scrapers similar to the Oldowan set found in the Olduvai Gorge, Tanzania. This implies that early humans with primitive technology were able to expand out of Africa, said Lordkipanidze.

Ferring added that although the stone tools are of the Oldowan set, "many of them show careful selection of the better raw materials located in the flanking valleys, and a number of the cores have been intensively reduced to maximize the number of flakes that were removed—I don't think they were stupid."

The Dmanisi evidence calls into question older theories on who left Africa first and why they left, said Ferring. Now scientists must ask the question: If not brain power and tool technology, what did enable early humans to leave Africa?

Lordkipanidze and colleagues suggest that the answer lies in anatomy and ecology, but say that without further study and discussion within the scientific community no conclusions can be drawn.

"My feeling has always been that it was the acquisition of modern body form and the consequent emancipation of hominids from the forest fringes and woodlands that allowed the spread of early humans to begin," said Ian Tattersall, an anthropologist at the American Museum of Natural History in New York City.

Stringer suggests that 1.8 million years ago the environment at the Dmanisi site may have been much more like that of East Africa.

"Thus these early humans may have just expanded their range, remaining in a rather familiar environment," he said. "However, greater reliance on tools and meat eating probably also facilitated the expansion."

Lordkipanidze says he hopes that further excavations at Dmanisi, which are continuing this summer, will reveal skeletal remains that will help answer some of these questions. "It is feasible that we will find some part of the body," he said.

The excavations at Dmanisi are funded in part by a grant from the National Geographic Society's Committee for Research and Exploration.

striblue

07-10-2002, 09:28 PM

Fred..that's great stuff... love reading about it.. Incidently, I really wanted to be an archeologist instead of what I am doing...more specifically an Eqyptologist. By the way ,when I am fishing on the deserted beaches of the Cape I am always on the lookout for shell midens...places where ancient indians would discard food scraps and the like..like an old garbage dump... also just south of Provincetown, at High Head ,if you dig a couple feet under the sand you can find shell fossils.... this is because High head is the ancient shore line before the sands of the Provincelands built up and is actually the results of the glacial morain.

fredaevans

07-10-2002, 10:08 PM

Lived in Southern BC in an area now called Twassan (well, close to the spelling... help me out here Dana). Accross the road was, we 'discovered' years ago was an Indian Potlatch ground. Very cool as a kid (we're talking 8-10 years old) to putt/dig through this area and find "finds." Cus. Pete always found the really good stuff like jaw bones, arrow heads, etc., ... I just turned up a lot of dirt; he got the 'goodies.'

Now a Condo complex if memory serves (Dana/Tyler would know for sure).

Life as a kid in the 'wilds' of BC was a good thing. Medford about as close as you can get. "Traffic jam" is still 6-7 cars ahead of you at the traffic light. On the river this morning at about 5:45am; zero people other than a jet guide boat that ran up the river. Interesting thing is "he" wasn't where 'local custom for a motor boat' was supposted to be. Legal yes, do you do that no. Interesting as this was the same fellow I sent off the letter to the "authorities" about being a complete ass. OSP even had a 'chat' with the fellow; obviously didn't "stick."
:smokin:

Grampa Spey

07-10-2002, 11:52 PM

I'm in the process of looking for a Spey Rod to fish for kings in N. Kali and your backyard. I, also would like to use it for cohos down stream in the lower Rogue this Sep/Oct..

What is your opinion re the Sage 10 weight Euro Spey Rod 10151 for Kings and Coho in your area. and in the rivers of N. Kali..

Thanks.

Dave

timwatts

07-11-2002, 05:34 AM

That is good stuff. We were up on the Kennebec a couple weeks ago and came across a bank of exposed marine clay. It looked like low tide at the beach, the shore was littered with sea shells. This would not be unusual along the coast but we were sixty miles inland above Augusta. Apparently the shells were left from the post glacial period when this area was an inland sea between twelve or fourteen thousand years ago. I am with you John, being an archaeologist would be a fascinating occupation.

pmflyfisher

07-11-2002, 08:26 AM

Fred,

I thought we agreed no more comments on the rural Medford, OR lifestyle, which just antagonizes us metropolitan area type folks. BTW an hour drive from Chicago I can be in that same rural life style, but without mountains and no steelhead or good fly fishing rivers. Have to go 2 to 3 hours for that.

As a kid growing up back east we had several areas we could find old indian arrowheads and revolutionary war items if you knew where the continental army camped in NJ, NY, PA.

Up in Michigan I found an old salmon spearing fork on the yes you know, the PM. Found it in the river. Quite a catch. Then several years later my wife decided to clean the garage again while I was not present and guess where that went.:eek: :eek:

Hal

fredaevans

07-11-2002, 11:32 AM

would be a great match. You can dry line, swing up to 300 grain RIO Big Boys, etc. with that rod.

Fred.

PS: The fall kings are already showing up in good numbers in the lower river in Gold Beach area. Ditto with summer runs and half pounders.